Swift/XRT, Chandra and XMM-Newton observations of IGR J17091-3624 as it returns into quiescence

Abstract

IGR J17091-3624 is a low mass X-ray binary (LMXB) which received wide attention from the community thanks to its similarities with the bright black hole system GRS 1915+105. Both systems exhibit a wide range of highly structured X-ray variability during outburst, with time scales from few seconds to tens of minutes, which make them unique in the study of mass accretion in LMXBs. In this work we present a general overview into the long-term evolution of IGR J17091-3624, using Swift/XRT observations from the onset of the 2011-2013 outburst in February 2011 to the end of the last bright outburst in November 2016. We found 4 re-flares during the decay of the 2011 outburst, but no similar re-flares appear to be present in the latter one. We studied in detail the period with the lowest flux observed in the last 10 years, just at the tail end of the 2011-2013 outburst, using Chandra and XMM-Newton observations. We observed changes in flux as high as a factor of 10 during this period of relative quiescence, without strong evidence of softening in the spectra. This result suggests that the source has not been observed at its true quiescence so far. By comparing the spectral properties at low luminosities of IGR J17091-3624 and those observed for a well studied population of LMXBs, we concluded that IGR J17091-3624 is most likely to host a black hole as a compact companion rather than a neutron star.

13 pages, 6 figures, 3 tables; To be published in MNRAS (Accepted 2020 July 1)

References in corpus (20)

• X-ray Properties of Black-Hole Binaries
• An online repository of Swift/XRT light curves of GRBs
• Thermonuclear (type-I) X-ray bursts observed by the Rossi X-ray Timing Explorer
• Advection-Dominated Accretion and the Black Hole Event Horizon
• A radio-emitting outflow in the quiescent state of A0620-00: implications for modelling low-luminosity black hole binaries
• Determination of mass of IGR J17091-3624 from "Spectro-Temporal" variations during onset-phase of the 2011 outburst
• The Quiescent X-ray Spectrum of Accreting Black Holes
• SAX J1808.4-3658: high resolution spectroscopy and decrease of pulsed fraction at low energies
• A NICER look at the state transitions of the black hole candidate MAXI J1535-571 during its reflares
• Zooming in on a sleeping giant: milliarcsecond HSA imaging of the black hole binary V404 Cyg in quiescence
• Detection of X-ray spectral state transitions in mini-outbursts of black hole transient GRS 1739-278
• Rapidly evolving disk-jet coupling during re-brightenings in the black hole transient MAXI J1535-571
• Spectral states of the X-ray binary IGR J17091--3624 observed by INTEGRAL and RXTE
• Discovery of GRS 1915+105 variability patterns in the Rapid Burster
• Spectral and Timing Properties of IGR J17091-3624 in the Rising Hard State During its 2016 Outburst
• The quasi-persistent neutron star soft X-ray transient 1M 1716-315 in quiescence
• Period doubling and non-linear resonance in the black hole candidate IGR J17091-3624 ?
• Simultaneous detection of an intrinsic absorber and a compact jet emission in the X-ray binary IGR J17091-3624 during a hard accretion state
• Variable quiescent state for the neutron-star X-ray transient SAX J1750.8-2900: not such a hot neutron star after all?
• SAX J1808.4-3657 in Quiescence: A Keystone for Neutron Star Science

Cited by in corpus (3)

• Modified models of radiation pressure instability in application to 10, 10${}^5$, and 10${}^7$ $M_{\odot }$ accreting black holes
• Low-Mass X-ray Binaries
• The INTEGRAL view on Black Hole X-ray Binaries